Recent studies have focused on the importance of the spectrum management. One of the recent proposals is to share the common pool of spectrum efficiently between multiple radio access networks.
Previously-considered methods for flexible use of spectrum include four different levels of spectrum management techniques in three different time scales: Spectrum Sharing and Coexistence (a couple of hours or days), Long Term (LT) Spectrum Assignment (a couple of minutes), Short Term (ST) Spectrum Assignment (one second) and fast dynamic Channel Allocation (10 ms time scale or even below). One of the entities included in this method is the concept of a gateway, which provides for long term spectrum assignment and some radio resource management (RRM) algorithms. The concept is illustrated in FIG. 1. The gateway is a central entity considered to be in charge of negotiations related to long term spectrum management. It is assumed that the one gateway is assigned to each radio access network (RAN).
The time granularity of spectrum functionalities is shown in FIG. 2. While the three functionalities of Spectrum Sharing and Coexistence, LT Spectrum Assignment and ST Spectrum Assignment are responsible for defining the amount of spectrum available at common spectrum pool and shaping the boundaries of spectrum in a longer time scale, dynamic Channel Allocation divides the final available spectrum determined by ST Spectrum Assignment (e.g. just borrowed from another cell) into radio sub-channels and decides which radio sub-channel would be allocated to which radio entity on a fast “ms” basis in response to radio channel and traffic variation.
In a spectrum-sharing scenario, efficient interference management will play a crucial role in efficient sharing and utilization of spectrum between the trading parties. Severe interference from one system on other system may lead to an inability to share the spectrum. To avoid the interference from one system to another, an exclusion zone has been considered, as shown in FIG. 3. Within an exclusive zone, spectrum sharing or flexible use of spectrum is forbidden to avoid interference from one system to another. For example, the exclusion zone may provide for protection of a satellite receiver as a primary system.